As antimicrobial proteins derived from insects, nearly 150 proteins have been found in many kinds of insects. Among these proteins, those reported to be active against filamentous fungi include drosomycin from Diptera insects (J. Biol. Chem., 1994; 269 (52): 33159–33163), heliomicin from Lepidoptera insects (J. Biol. Chem. 1999; 274 (14): 9320–9326), thanatin from Hemiptera insects (Proc. Natl. Acad. Sci. USA 1996; 93: 9320–9326) etc.
As antimicrobial peptides from the coconut rhinoceros beetle (Oryctes rhinoceros) i.e. a Coleoptera insect, on one hand, there are reported tryphacin (JP-A 8-283291), oryctin (JP-A8-283292), rhinocerasin (JP-A8-283294) and defensin (Eur. J. Biochem. 1999; 266: 616–623), but antimicrobial proteins active against filamentous fungi are still not known.
In recent years, it is attempted to confer disease resistance by introducing antimicrobial protein genes obtained from insects into plants. Tobacco plants transformed with sarcotoxin IA obtained from SARCOPHAGA PEREGRINA (Mol. Plant. Microbe. Interact. 2000; 13(8) 860–868), rice plants transformed with cecropin B obtained from silkworms (FEBS Letters 2000; 484: 7–11) etc. are reported but still not practically used. This is probably because the gene introduced into the plant was not obtained as a gene of a protein active against plant-pathogenic filamentous fungi exerting significant damage to the plant. Accordingly, it is desired that an antimicrobial protein which is more active against filamentous fungi than the conventional antimicrobial proteins, and its gene, are identified and used.
As the industrial antimicrobial/antifungal agents, an organic nitrogenous compound, an organic nitrogenous sulfurous compound, an organohalogen compound, a nitrogen-containing aliphatic polymer and a heavy metal-coordinated compound have been used. However, these compounds contain chemicals which are stimulative and problematic in the labor safety law, chemicals used in a large amount to cause a problem from the viewpoint of environmental protection, chemicals releasing formalin or halogens to cause worry about their influence on the human body and about environmental pollution, and chemicals by which environmental pollution with heavy metals is worried about, and it cannot be said that the industrial antimicrobial/antifungal agents are composed exclusively of preferable chemicals.
In medical fields, on one hand, multiple drug resistance microorganisms which are resistant to, for example, antibiotics such as methicillin and vancomycin come to be problematic, and there is demand for useful chemicals effective against these multiple drug resistance microorganisms.